Naslov
Long-term isotope records of precipitation in Zagreb, Croatia

Autori
Krajcar Bronić, Ines ; Barešić, Jadranka ; Borković, Damir ; Sironić, Andreja ; Lovrenčić Mikelić, Ivanka ; Vreča, Polona

Izvornik
Water (2073-4441) 12 (2020), 1; 226, 29

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
precipitation ; Zagreb ; Croatia ; stable isotope ratios ; deuterium excess ; tritium ; LMWL

Sažetak
The isotope composition of precipitation has been monitored in monthly precipitation at Zagreb, Croatia, since 1976. Here, we present a statistical analysis of available long-term isotope data (3H activity concentration, delta2H, delta18O, and deuterium excess) and compare them to basic meteorological data. The aim was to see whether isotope composition reflected observed climate changes in Zagreb: a significant increase in the annual air temperature and larger variations in the precipitation amount. Annual mean delta18O and delta2H values showed an increase of 0.017 ‰ and 0.14 ‰ per year, respectively, with larger differences in monthly mean values in the first half of the year than in the second half. Mean annual d-excess remained constant over the whole long-term period, with a tendency for monthly mean d-excess values to decrease in the first half of the year and increase in the second half due to the influence of air masses originating from the eastern Mediterranean. Changes in the stable isotope composition of precipitation thus resembled changes in the temperature, the circulation pattern of air masses, and the precipitation regime. A local meteoric water line was obtained using different regression methods, which did not result in significant differences between nonweighted and precipitation-weighted slope and intercept values. Deviations from the Global Meteoric Water Line GMWL (lower slopes and intercepts) were observed in two recent periods and could be explained by changes in climate parameters. The temperature gradient of delta18O was 0.33 ‰/°C. The tritium activity concentrations in precipitation showed slight decreases during the last two decades, and the mean A in the most recent period, 2012–2018, was 7.6 ± 0.8 Tritium Units (TU).

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Interdisciplinarne prirodne znanosti

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